ABSTRACT
Recent experimental data indicate that parental magmas of the anorthosite-mangerite-charnockite suite probably encompass a large continuum of compositions ranging from high-Al basalts to more ferroan and potassic compositions, represented by the primitive jotunites (hypersthene-bearing monzodiorites). Polybaric fractional crystallization and synemplacement deformation in rising anorthosite diapirs lead to relatively Mg- and Cr-rich ilmenite deposits. The high contents in Cr and Mg are deleterious for the new chlorination process that tends to substitute to the classical sulfatation process used in the TiO2 pigment industry. The reaction regularly lowers the hematite content of the ilmenite solid solution and the TiO2 and the Al-spinel contents of the magnetite solid solution. The Mg content of ilmenite also decreases subsolidus, particularly in the Bjerkreim-Sokndal intrusion, possibly through reactions with pyroxenes, though no reaction rims can be observed.
